The dose-related hyper-and-hypokalaemic effects of salbutamol and its arrhythmogenic potential

Hyperkalemia in liver transplantation

Hyperkalemia commonly occurs in patients undergoing liver transplantation. The intraoperative course of liver transplant often involves hemodynamic and metabolic derangements leading up to liver reperfusion. Potassium levels can rise to dangerous levels immediately after reperfusion. The consequences of intraoperative hyperkalemia include risk of malignant arrhythmias and cardiac arrest. This review explores the numerous causes of hyperkalemia, including contributing surgical and anesthetic factors. The authors also discuss various treatment options and surgical techniques to manage perioperative hyperkalemia. It is important for anesthesiologists to understand the implications and management of hyperkalemia to optimize patients and reduce the risk of an intraoperative cardiac arrest.

Drug-induced hypokalemia: an analytical study based on real-world drug monitoring data

BACKGROUND

Drug-induced hypokalemia is often associated with adverse clinical outcomes, and unfortunately, the inability to fully understand the drugs that cause hypokalemia puts us in a passive position. This study applies pharmacovigilance data to present a panorama of suspected medications associated with hyperkalemia.

RESEARCH DESIGN AND METHODS

This study used disproportionality analysis to mine adverse events in OpenFDA, identified all suspected drugs that caused hypokalemia, and coded and classified the suspected drugs according to the Anatomical Therapeutic Chemical (ATC) classification system.

RESULTS

There are 19755 reports related to drug-induced hypokalemia. The majority of individuals with hypokalemia are females, with a concentrated age range of 65 to 84 years old. After the occurrence of hypokalemia, 8.02% died due to hypokalemia. This study identified 1141 suspected drugs, and among the top 50 drugs, 32 drugs did not include hypokalemia in their instructions. All suspected drugs can be categorized into 73 subgroups according to the ATC classification system.

CONCLUSIONS

By mining the OpenFDA database, we have identified all suspected drugs that cause hypokalemia and conducted a comprehensive evaluation. The instructions for most of the suspected drugs do not focus on hypokalemia. When the treatment regimen includes other drugs that can directly/indirectly cause a decrease in blood potassium, we recommend actively monitoring blood potassium when using suspected drugs.

Inhaled Short-Acting Beta Agonist Treatment-Associated Supraventricular Tachycardia in Children: Still a Matter of Concern in Pediatric Emergency Departments?

Inhaled selective short-acting β-2 agonists (SABA), such as salbutamol, are the rescue treatment of choice for the relief of symptoms of acute asthma exacerbations: one of the leading causes of pediatric emergency department admission and hospitalization. Cardiovascular events, including supraventricular arrhythmias, are the most frequent side effects reported with inhaled SABA in children with asthma and are the main reason for a continuing debate about their safety, despite their widespread use. Although supraventricular tachycardia (SVT) is the most common potentially serious dysrhythmia in children, the incidence and risk factor of SVT after SABA administration is currently unknown. We here reported three cases and conducted a review of the literature in an attempt to gain insight into this issue.

Effect of inhaled albuterol on whole blood potassium concentrations in dogs

BACKGROUND

Albuterol by inhalation (IH) is a common treatment for hyperkalemia in humans but its effect on blood potassium concentrations in dogs is unknown.

OBJECTIVE

Determine whether albuterol (IH) decreases blood potassium concentrations in healthy normokalemic dogs and if effects are dose-dependent.

ANIMALS

Ten healthy dogs.

METHODS

Prospective, crossover experimental study. Albuterol sulfate was administered at a low-dose (90 μg) in phase I and, 7 days later, high-dose (450 μg) in phase II. Blood potassium and glucose concentrations (measured via blood gas analyzer) and heart rates were obtained at baseline and then 3, 5, 10, 15, 30, 60, 90, 120, 180, and 360 minutes after inhaler actuation.

RESULTS

Blood potassium concentrations decreased rapidly after albuterol delivery with a significant reduction compared to baseline within 30 minutes in both phases (P = .05). The potassium nadir concentration of phase I occurred at 60 minutes (mean, SD; 4.07 mmol/L, 0.4) and was significantly decreased from baseline, (4.30 mmol/L, 0.3; t(9) = 2.40, P = .04). The potassium nadir concentration of phase II occurred at 30 minutes (mean, SD; 3.96 mmol/L, 0.39) and was also significantly decreased from baseline, (4.33 mmol/L, 0.4; t(9) = 2.22, P = .05). The potassium nadir concentration decreased by 0.1 mmol/L for each 10 μg/kg increase in dose of albuterol (P = .01). Five dogs had ≥1 hyperglycemic measurement (ie, >112 mg/dL). No median heart rate was tachycardic nor was any mean blood glucose concentration hyperglycemic at any time point.

CONCLUSION AND CLINICAL IMPORTANCE

Albuterol IH decreases blood potassium concentrations in a dose-dependent manner without clinically meaningful alterations to heart rate or blood glucose concentrations in healthy dogs. The mean decrease in potassium concentration at the high-dose of albuterol was modest (0.38 mmol/L).

Novel approaches to management of hyperkalaemia in kidney transplantation

PURPOSE OF REVIEW

Medications used frequently after kidney transplantation, including calcineurin inhibitors, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, beta blockers and antimicrobials, are considered the leading culprit for posttransplant hyperkalaemia in recipients with a well functioning allograft. Other risk factors include comorbidities such as diabetes, hypertension and heart failure; and consumption of a potassium-enriched diet. We review the mechanisms for hyperkalaemia following kidney transplantation that are addressed using nonpharmacological and pharmacological interventions. We also discuss emerging therapeutic approaches for the management of recurrent hyperkalaemia in solid organ transplantation, including newer potassium binding therapies.

RECENT FINDINGS

Patiromer and sodium zirconium cyclosilicate are emerging potassium binders approved for the treatment of hyperkalaemia. Patiromer is a polymer that exchanges potassium for calcium ions. In contrast, sodium zirconium cyclosilicate is a nonpolymer compound that exchanges potassium for sodium and hydrogen ions. Both agents are efficacious in the treatment of chronic or recurrent hyperkalaemia and may result in fewer gastrointestinal side effects than older potassium binders such as sodium polystyrene sulfonate and calcium polystyrene sulfonate. Large-scale clinical studies have not been performed in kidney transplant patients. Patiromer may increase serum concentrations of tacrolimus, but not cyclosporine. Sodium zirconium cyclosilicate does not appear to compromise tacrolimus pharmacokinetics, although it may have a higher sodium burden.

SUMMARY

Patiromer and sodium zirconium cyclosilicate may be well tolerated options to treat asymptomatic hyperkalaemia and have the potential to ease potassium dietary restrictions in kidney transplant patients by maintaining a plant-dominant, heart-healthy diet. Their efficacy, better tolerability and comparable cost with respect to previously available potassium binders make them an attractive therapeutic option in chronic hyperkalaemia following kidney transplantation.

Use of ICS/LABA (extra-fine and non-extra-fine) in elderly asthmatics

Age represents an exclusion criterion in randomized clinical trials designed to test the efficacy and safety of inhaled drugs in asthma. As a consequence, data on efficacy and safety of inhaled corticosteroid (ICS) and long-acting β2 agonist (LABA) combinations in elderly asthmatics are scanty. Older age is associated with an increased proportion of comorbid conditions; in addition, all organ functions undergo a process of senescence, thus reducing their ability to metabolize the agents. Overall, these age-associated conditions may variably, and often unpredictably, affect the metabolism and excretion of respiratory drugs. However, pharmacological treatment of asthma does not follow specific recommendations in the elderly. In the elderly, the ICS/LABA combinations may carry an increased risk of local indesiderable effects, primarily due to the lack of coordination between activation of the device and inhalation, and systemic adverse events, mainly due to the greater amount of active drug that is available because of the age-associated changes in organ functions as well as drug-to-drug and drug-to-concomitant disease interactions. The extra-fine formulations of ICSs/LABAs, which allow for a more favorable drug deposition in the lungs at a reduced dose, may contribute to overcome this issue. This review revises the efficacy and safety of treatment with ICSs/LABAs, focusing on the main pharmacodynamic and pharmacokinetic properties of the drugs and highlighting the potential risks in the elderly asthmatic population.

Drug-induced effects on cardiovascular function in pentobarbital anesthetized guinea-pigs: invasive LVP measurements versus the QA interval

INTRODUCTION

Evaluation of drug-related effects on cardiovascular function is part of the core battery described in the ICH S7A guideline. Anesthetized guinea-pigs are excellent models for the evaluation of drug-induced prolongation of ventricular repolarization; however less information is available regarding other cardio-hemodynamic parameters in this model. The current study aimed to document cardio-hemodynamic responses in anesthetized guinea-pigs after administration of a number of reference drugs with known pharmacological actions.

METHODS

Experiments were carried out in closed chest pentobarbital anesthetized female guinea-pigs. Compounds were administered intravenously while arterial blood pressure, left ventricular pressure (LVP) and the electrocardiogram were measured continuously. The rate of LVP contraction (LV dP/dt(max)) was used to evaluate cardiac performance; and was compared to the QA interval; which has previously been proposed as an indirect measurement of cardiac function.

RESULTS

Baseline values for heart rate and blood pressure were lower in anesthetized animals compared to literature data of conscious guinea-pigs. Heart rate increased after administration of adrenaline, isoprenaline and salbutamol, but not after L-phenylephrine. Verapamil and amiodarone decreased heart rate and blood pressure. Zatebradine infusion led to a decrease in heart rate with minimal effects on blood pressure. Sodium nitroprusside (SNP) caused a reduction in mean blood pressure at higher doses followed by reflex tachycardia. Both adrenaline and L-phenylephrine increased arterial blood pressure. Furthermore, adrenaline, isoprenaline and salbutamol increased LV dP/dt(max) and decreased the QA interval. L-phenylephrine increased LV dP/dt(max), but transiently prolonged the QA interval. Both verapamil and amiodarone decreased LV dP/dt(max) and prolonged the QA interval, whereas zatebradine did not affect this parameter.

DISCUSSION

In addition to its utility for the assessment of test compounds on ventricular repolarization the pentobarbital anesthetized guinea-pig model shows promise for early stage cardio-hemodynamic screening. Furthermore, the QA interval shows potential for prediction of adverse effects on cardiac contractility.

Pharmacology and therapeutics of bronchodilators

Bronchodilators are central in the treatment of of airways disorders. They are the mainstay of the current management of chronic obstructive pulmonary disease (COPD) and are critical in the symptomatic management of asthma, although controversies around the use of these drugs remain. Bronchodilators work through their direct relaxation effect on airway smooth muscle cells. at present, three major classes of bronchodilators, β(2)-adrenoceptor (AR) agonists, muscarinic receptor antagonists, and xanthines are available and can be used individually or in combination. The use of the inhaled route is currently preferred to minimize systemic effects. Fast- and short-acting agents are best used for rescue of symptoms, whereas long-acting agents are best used for maintenance therapy. It has proven difficult to discover novel classes of bronchodilator drugs, although potential new targets are emerging. Consequently, the logical approach has been to improve the existing bronchodilators, although several novel broncholytic classes are under development. An important step in simplifying asthma and COPD management and improving adherence with prescribed therapy is to reduce the dose frequency to the minimum necessary to maintain disease control. Therefore, the incorporation of once-daily dose administration is an important strategy to improve adherence. Several once-daily β(2)-AR agonists or ultra-long-acting β(2)-AR-agonists (LABAs), such as indacaterol, olodaterol, and vilanterol, are already in the market or under development for the treatment of COPD and asthma, but current recommendations suggest the use of LABAs only in combination with an inhaled corticosteroid. In addition, some new potentially long-acting antimuscarinic agents, such as glycopyrronium bromide (NVA-237), aclidinium bromide, and umeclidinium bromide (GSK573719), are under development, as well as combinations of several classes of long-acting bronchodilator drugs, in an attempt to simplify treatment regimens as much as possible. This review will describe the pharmacology and therapeutics of old, new, and emerging classes of bronchodilator.

Inhaled beta-2 agonist salbutamol for the treatment of transient tachypnea of the newborn

OBJECTIVE

To evaluate the efficacy of inhaled salbutamol, a beta-2 adrenergic agonist, for the treatment of transient tachypnea of the newborn (TTN) and to determine whether inhaled salbutamol is safe in newborn infants.

STUDY DESIGN

Inhaled salbutamol or normal saline solution was administered to 54 infants with gestational ages ranging from 34 to 39 weeks and TTN. The response to salbutamol therapy was evaluated by determining respiratory rate, clinical score of TTN, level of respiratory support, and fraction of inspired oxygen before and at 30 minutes and 1 and 4 hours after salbutamol nebulization.

RESULTS

Among the 54 infants with TTN, 32 received salbutamol and 22 received normal saline solution. After one dose, the salbutamol group showed significant improvements in respiratory rate, clinical score of TTN, fraction of inspired oxygen, and level of respiratory support (P < .05). After treatment, the mean pH, partial pressure of arterial oxygen, and partial pressure of arterial carbon dioxide values were better in the salbutamol group when compared with the placebo group (P < .05). Duration of hospitalization in the neonatal intensive care unit was also shorter for the salbutamol group (P < .05).

CONCLUSION

Inhaled salbutamol treatment was effective with respect to both clinical and laboratory findings of TTN and without adverse events.

Salbutamol to facilitate management of acute hyperkalemia in liver transplantation: a case report

PURPOSE

Acute hyperkalemia is a frequent, potentially life-threatening complication in orthotopic liver transplantation (OLT). We describe a case of acute hyperkalemia during the pre-anhepatic stage that remained persistent despite conventional treatment, including calcium salts, insulin and glucose, sodium bicarbonate, and furosemide.

CLINICAL FEATURES

A 50-yr-old man with end-stage hepatitis B liver cirrhosis underwent living donor liver transplantation, receiving a right lobe graft donated by his son. The initial serum potassium concentration was 4.6 mEq l(-1). Despite conventional management, the serum potassium concentration increased to 6.6 mEq l(-1), intraoperatively. Since about 90 min elapsed from the division of the hepatic artery and the portal vein to the clamping of the suprahepatic inferior vena cava, the persistent hyperkalemia may have resulted from loss of potassium from ischemic liver cells into the systemic circulation. After incorporating nebulized salbutamol, a selective beta(2)-agonist, into the combined therapeutic regimen (sodium bicarbonate and insulin with glucose), the serum potassium concentrations rapidly normalized.

CONCLUSIONS

This case suggests that acute and relatively refractory hyperkalemia can develop when surgical interruption of hepatic inflow is prolonged during hepatectomy in patients undergoing OLT using the piggyback technique. In such situations, incorporating nebulized salbutamol with a conventional anti-hyperkalemia strategy can provide an effective therapeutic option to treat hyperkalemia, even during the anhepatic stage.

β-2 Adrenergic Receptor Diplotype Defines a Subset of Salt-Sensitive Hypertension

Two genetic variants of the beta-2 adrenergic receptor, 46G>A and 79C>G, affect agonist-mediated receptor downregulation and vascular reactivity. We determined whether these variants were associated with hypertension, per se, blood pressure response to dietary sodium, 2 forms of salt-sensitive hypertension (low renin and nonmodulation), and the activity of the renin-angiotensin-aldosterone system. Included are 280 hypertensive and 65 normotensive white subjects who had the 2 beta-2 adrenergic receptor genotypes available. Of all subjects, 171 hypertensive and 48 normotensive subjects had complete data for intermediate phenotyping and blood pressure evaluation on high- and low-sodium balance. The beta-2 adrenergic receptor variants were not associated with hypertension per se. However, among hypertensive subjects, the change (from low to high sodium balance) in mean arterial pressure differed significantly by genotype and by diplotype. Compared with all of the other diplotypes combined, 46AA/79CC was associated with a greater change in blood pressure. Furthermore, this diplotype was associated with low-renin (LR) hypertension (identifying 32% of the LR hypertensives), higher plasma aldosterone, and lower plasma renin and serum potassium levels. In conclusion, the 46AA/79CC diplotype is associated with greater blood pressure response to dietary sodium and higher odds of LR hypertension. We propose that the mechanism for the observed association is inadequate suppression of aldosterone with salt intake, implicating the beta-2 adrenergic receptor in the regulation of aldosterone secretion. This hypothesis was confirmed in isolated glomerulosa cells, where beta-2 adrenergic receptor stimulation increased aldosterone secretion, whereas blockade reduced the stimulated aldosterone response. Importantly, this association could only be detected with an intermediate and not a distant phenotype.

Beta-adrenoceptor responses of the airways: for better or worse?

Beta2-adrenoceptor agonists are the first-line treatment of asthma and chronic obstructive pulmonary disease (COPD), in which a short-acting beta2-adrenoceptor agonist is used as required for relief of bronchoconstriction. A long-acting beta2-adrenoceptor agonist may be added to an inhaled corticosteroid as step 3 in the management of chronic asthma. Long-acting beta2-adrenoceptor agonists may also be added in treatment of COPD. This review examines the beneficial and detrimental effects of beta2-adrenoceptor agonists. The beneficial effects of beta2-adrenoceptor agonists are mainly derived from their bronchodilator activity which relieves the bronchiolar narrowing and improves air flow. The potential anti-inflammatory actions of stabilizing mast cell degranulation and release of inflammatory and bronchoconstrictor mediators, is considered. Other potential beneficial responses include improvements in mucociliary clearance and inhibition of extravasation of plasma proteins that is involved in oedema formation in asthma. The side effects of beta2-adrenoceptor agonists are primarily related to beta2-adrenoceptor-mediated responses at sites outside the airways. Of major concern has been the development of tolerance and this is discussed in relation to incidence of increased morbidity and mortality to asthma over the past three decades. A clinical aspect of beta2-adrenoceptor pharmacology in recent years has been the recognition of genetic polymorphism of the receptor and how this affects responses to and tolerance to beta2-adrenoceptor agonists. A controversial feature of beta2-adrenoceptor agonists is their stereoisomerism and whether the inactive (S)-isomer of salbutamol had detrimental actions in the commercially used racemate. The consensus is that despite these adverse properties, beta2-adrenoceptor agonist remains the most useful pharmacological agents in the management of asthma and COPD.

The administration of beta2-agonists for paediatric asthma and its adverse reaction in Australian and New Zealand emergency departments: a cross-sectional survey

AIM

To determine the current use of beta2-agonists, in particular salbutamol, for the management of acute asthma in children in emergency departments throughout Australia and New Zealand.

METHODS

A cross-sectional survey using a questionnaire that sought to determine the current use of salbutamol and any adverse drug reactions in paediatric emergency departments.

RESULTS

Out of 37 hospitals eligible as paediatric emergency departments, 33 (89.1%) responded to the survey, 54.5% having guidelines for the management of acute asthma. Of the paediatric emergency departments surveyed, 45.5% used metered-dose inhaler spacer combination in the treatment of mild to moderate asthma. All paediatric emergency departments used nebulized salbutamol for acute severe asthma. In addition, 85% of paediatric emergency departments used continuous-infusion intravenous salbutamol in unresponsive patients, 63.6% administering a single-dose intravenous salbutamol bolus before commencing the infusion. District paediatric emergency departments were more likely to treat with continuous-infusion intravenous salbutamol outside of the intensive care unit. Clinical unresponsiveness to inhaled salbutamol and clinical improvement were the reported criteria in all paediatric emergency departments for the use and cessation of intravenous salbutamol. Adverse drug reactions were common: tremor (90%), hypokalaemia (45.5%) and supraventricular tachycardia (21%), particularly if continuous-infusion intravenous salbutamol administered. Eight deaths from asthma were reported, none being related to adverse drug reactions.

CONCLUSION

We report a wide variation of salbutamol use in paediatric emergency departments and a high prevalence of type A adverse drug reactions when continuous-infusion intravenous salbutamol therapy was administered. More evidence is needed on the clinical significance of the adverse effects reported in this study and optimal doses for the safe use of continuous-infusion intravenous salbutamol therapy in paediatric emergency departments.

Experimental hyperkalaemia in rabbits: effects of salbutamol and norepinephrine treatments on blood biochemistry and electrocardiography

The effects of salbutamol and norepinephrine on the electrocardiogram (ECG), serum potassium level and enzyme activities were studied in rabbits with hyperkalaemia; norepinephrine and salbutamol may be therapeutically useful. For induction of hyperkalaemia, 300 mM KCl solution was used and then isotonic saline solution containing 6 microg salbutamol and 3.9 microg norepinephrine per ml were administered. Norepinephrine and salbutamol decreased the serum potassium from 7.36 +/- 0.26 and 7.21 +/- 0.31 mmol/L to 5.62 +/- 0.27 and 4.35 +/- 0.33 mmol/L, respectively, and caused the ECG changes (flatness of P wave, widening of QRS complex and bradycardia) to return to the control conditions (time 0). Norepinephrine, but not salbutamol, decreased the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) to the control levels. These results suggest that monitoring of the enzyme activities might be useful as it yields indexes suitable for evaluating the therapeutic approach with norepinephrine in hyperkalaemia.

Efficacy of albuterol inhalation in treatment of hyperkalemia in premature neonates

OBJECTIVE

To evaluate the efficacy of inhaled albuterol for treatment of hyperkalemia in premature neonates by conducting a prospective, randomized placebo-controlled and double-blinded clinical trial.

STUDY DESIGN

Neonates <2000 g receiving mechanical ventilation with central serum potassium > or =6.0 mmol/L (6.0 mEq/L), were randomly assigned to treatment or placebo groups. Albuterol (400 microg) or saline was given by nebulization. The dose was repeated every 2 hours until the potassium level fell below 5 mmol/L (maximum 12 doses) or there were signs of toxicity.

RESULTS

Nineteen patients completed the study (8 in the albuterol and 11 in the saline group). Serum potassium levels declined rapidly in the first 4 hours in the albuterol group, from 7.06 +/- 0.23 mmol/L to 6.34 +/- 0.24 mmol/L (P =.003) versus no significant change in the saline group (6.88 +/- 0.18 mmol/L to 6.85 +/- 0.24 mmol/L; P =.87). At 8 hours, the fall continued to be greater in the albuterol group versus the saline group (5.93 +/- 0.3 mmol/L and 6.35 +/- 0.22 mmol/L, respectively; P =.04).

CONCLUSION

Albuterol inhalation may be useful in rapidly lowering serum potassium levels in premature neonates.

Salbutamol metered-dose inhaler with spacer for hyperkalemia: how fast? How safe?

OBJECTIVE

To determine the efficacy of inhaled salbutamol (rapidly delivered, using a metered-dose inhaler with a spacer device [MDI-S]) in lowering the serum potassium levels in patients with hyperkalemia.

DESIGN

A randomized, double-blind, placebo-controlled trial.

PATIENTS

Seventeen chronic renal failure patients referred to the Nephrology Unit between October 1, 1997 and March 31, 1998 for hemodialysis were randomized.

INTERVENTION AND RESULTS

Group 1 received salbutamol followed by a placebo. Group 2 received a placebo followed by salbutamol. Each patient inhaled 1,200 microg salbutamol or a placebo through an MDI-S within 2 min. Blood samples were obtained repeatedly before inhalation and after 1, 3, 5, 10, and 60 min. The pulse rate and blood pressure were repeatedly measured. Insulin levels were examined in a subset of patients (n = 10) before, and 1 and 5 min following inhalation. Salbutamol's known side effects, palpitation, tachycardia tremor, and headache, were recorded. Potassium levels rose after 1 min following the completion of treatment and then decreased steadily thereafter. A rise of > or = 0.1 mEq/L was seen in 10 of 17 patients (59%) during the treatment period and there was no change (0%) seen during the placebo period (p < 0.0001). Within 3 min after inhalation of salbutamol, potassium levels declined as a function of time. Potassium levels in those patients taking the placebo did not change as a function of time (p < 0.001). The difference between the placebo and the salbutamol-treated periods reached significance after 5 min (p < 0.05). The serum glucose levels rose following inhalation of salbutamol, with a significant rise after 3 min. The heart rate rose significantly within the first 5 min following inhalation. Serum insulin levels remained unchanged 1 min after inhalation; however, after 5 min, a significant elevation was detected.

CONCLUSION

Salbutamol inhalation of 1,200 microg, using an MDI-S, has a relatively rapid onset of action that induces a consistent reduction in serum potassium levels, starting 3 to 5 min following delivery. Unexpectedly, a paradoxical elevation was detected in serum potassium levels in the first minutes following inhalation. This effect, although minor (0.15 mEq/L above baseline), may cast some doubt on the role of salbutamol inhalation as the first treatment for excessive hyperkalemia.